Field of the Disclosure
The present disclosure relates to communications technology and more particularly to wireless communications services using digital modulation techniques.
Description of the Related Art
A typical wireless communications network uses digital modulation techniques (e.g., Quadrature Amplitude Modulation (QAM)) to increase the spectral efficiency (bps/Hz) of wireless communications. To increase the amount of data being communicated via QAM, the number of distinct amplitude levels used by the communication may be increased. However, to reduce or avoid degrading the communication reliability, an increase in the number of distinct amplitude levels must be accompanied by sufficient channel capacity, which may be quantified by a Signal-to-Interference-plus-Noise-Ratio (SINR) for a particular communications distance. In addition, the increase in the number of distinct amplitude levels increases the required transmit signal power. However, in a typical wireless communications system, the transmit signal power is limited by regulation. Thus, any increases in the number of distinct amplitude levels must be accompanied by shorter communications distances to maintain communications with an increased SINR. A reduction in radio communications distance may result in increased network costs due to an increase in the number of base stations and a decrease in cell size. Accordingly, improved techniques for increasing the spectral efficiency of a wireless communications system are desired.